diff options
Diffstat (limited to 'src/stem/mem/paging.c')
| -rw-r--r-- | src/stem/mem/paging.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/src/stem/mem/paging.c b/src/stem/mem/paging.c new file mode 100644 index 0000000..5ce3aae --- /dev/null +++ b/src/stem/mem/paging.c @@ -0,0 +1,121 @@ +#include "paging.h" +#include <bitset.h> +#include <stdlib.h> +#include <core/monitor.h> +#include "mem.h" +#include <core/sys.h> + +static struct bitset frames; + +struct page_directory *kernel_pagedir, *current_pagedir; + +/* ACCESSOR FUNCTIONS FOR STATIC BITSET */ +uint32_t frame_alloc() { + uint32_t free = bitset_firstFree(&frames); + bitset_set(&frames, free); + return free; +} + +void frame_free(uint32_t id) { + bitset_clear(&frames, id); +} + + +void paging_init(size_t totalRam) { + uint32_t i; + + frames.size = totalRam / 0x1000; + frames.bits = kmalloc(INDEX_FROM_BIT(frames.size)); + + kernel_pagedir = kmalloc(sizeof(struct page_directory)); + kernel_pagedir->tablesPhysical = kmalloc_page(&kernel_pagedir->physicalAddr); + for (i = 0; i < 1024; i++) { + kernel_pagedir->tables[i] = 0; + kernel_pagedir->tablesPhysical[i] = 0; + } + + for (i = 0xE0000000; i < mem_placementAddr; i += 0x1000) { + page_map(pagedir_getPage(kernel_pagedir, i, 1), frame_alloc(), 0, 0); + } + for (i = 0; i < (mem_placementAddr - 0xE0000000) / 0x100000; i++) { + kernel_pagedir->tablesPhysical[i] = kernel_pagedir->tablesPhysical[i + 896]; + kernel_pagedir->tables[i] = kernel_pagedir->tables[i + 896]; + } + + monitor_write("Page dir is at: "); + monitor_writeHex(kernel_pagedir->physicalAddr); + pagedir_switch(kernel_pagedir); + monitor_write("\nPaging started\n"); +} + +void paging_cleanup() { + uint32_t i; + for (i = 0; i < (mem_placementAddr - 0xE0000000) / 0x100000; i++) { + kernel_pagedir->tablesPhysical[i] = 9; + kernel_pagedir->tables[i] = 0; + } + monitor_write("Pages cleaned up\n"); +} + +void pagedir_switch(struct page_directory *pd) { + current_pagedir = pd; + asm volatile("mov %0, %%cr3" : : "r"(pd->physicalAddr)); + uint32_t cr0; + asm volatile("mov %%cr0, %0" : "=r"(cr0)); + cr0 |= 0x80000000; + asm volatile("mov %0, %%cr0" : : "r"(cr0)); +} + +uint32_t paging_fault(struct registers *regs) { + size_t addr; + asm volatile("mov %%cr2, %0" : "=r"(addr)); + monitor_write("PageFault "); + if (regs->err_code & 0x1) monitor_write("present "); + if (regs->err_code & 0x2) monitor_write("write "); + if (regs->err_code & 0x4) monitor_write("user "); + if (regs->err_code & 0x8) monitor_write("rsvd "); + if (regs->err_code & 0x10) monitor_write("instructionfetch "); + monitor_write("@"); monitor_writeHex(addr); monitor_write("\n"); + PANIC("Page fault"); + return 0; +} + +struct page *pagedir_getPage(struct page_directory *pd, uint32_t address, int make) { + address /= 0x1000; + uint32_t table_idx = address / 1024; + + if (pd->tables[table_idx]) { + return &pd->tables[table_idx]->pages[address % 1024]; + } else if (make) { + pd->tables[table_idx] = kmalloc_page(pd->tablesPhysical + table_idx); + memset((uint8_t*)pd->tables[table_idx], 0, 0x1000); + pd->tablesPhysical[table_idx] |= 0x07; + return &pd->tables[table_idx]->pages[address % 1024]; + } else { + return 0; + } +} + +void page_map(struct page *page, uint32_t frame, uint32_t user, uint32_t rw) { + if (page != 0 && page->frame == 0 && page->present == 0) { + page->present = 1; + page->rw = (rw ? 1 : 0); + page->user = (user ? 1 : 0); + page->frame = frame; + } +} + +void page_unmap(struct page *page) { + if (page != 0) { + page->frame = 0; + page->present = 0; + } +} + +void page_unmapFree(struct page *page) { + if (page != 0) { + if (page->frame != 0) frame_free(page->frame); + page->frame = 0; + page->present = 0; + } +} |